Apparatus for insulating conductors



- R, T. ADAMS mea Feb. 9, 1944 mvl-:NTR R.T. ADAMS,

b M ...d

4 Elin.)

Avronus June i7, 1947.

APPARATUS'FoR IHSULATING coxmuc'rons FIGJI Patented June 17, 1947APPARATUS FOR INSULATIN G CONDUCTORES Robert T. Adams, Baltimore, Md.,assis-nor to Western Electric Company, Incorporated, New York, N. Y., acorporation of New York Application February 9, 194i, Serial No. 521,6@

(i Claims. l

This invention relates to apparatus for insulating conductors.

In the manufacture of textile insulated conductors, it is sometimesnecessary to impregnate the textile coverings thereof with aWaterproofing and insulating material.

An object of the invention is to provide new and improved apparatus forinsulating con=` ductors. g

One device embodying the invention comprises a die having an openingprovided with hell-s shaped portions at each end thereof, meansiorheating the die, and means for feeding a thermoplastic material to theentrance of the opening.

A complete understanding of the invention may be obtained from thefollowing detailed description of a. specic embodiment thereof, whenread in conjunction with the appended drawings, in which:

Fig. l is a vertical elevation of an apparatus embodying the invention;

l through a knitting head il of a knitting machine of a. conventionaltype by a pair of feeding and guiding rollers i2i2. As the conductor lllis drawn through the knitting head il, a knitted textile covering i3 isformed over the conductor It.

The conductor i with the textile covering i3 formed thereon is drawn bya pair of grooved guiding and advancing rollers lilifi (Fig. l) througha die opening i5 (Fig. 2) formed in a die i6. The die it is secured in avertical opening Il formed in a die-supporting block it and issurrounded by an insert ill. The insert i9 consists of a heating coil2l, which is connected to a source of electric current (not shown) toheat the die it and a mass of a suitable electrical insulating 'butheat-conducting material surrounding the heating coil. A flange 22formed on the die-supporting block i8 serves to support the die I6 lbutis prevented from being heated by the coil 2l and the die it -fby alayer 213 of heat insulating material, such as asbestos. The layer 261also insulates the other portions lof the diesupporting block i8 fromthe insert le.

A pair of feed rollers 2'l-2l (Fig. 1) driven by suitable power means(not shown) serve to feed e. strip 29 of a thermoplastic material havingsuitable water prooiing and insulating qualities to the entrance of thedie opening it (Fig. 2)

where the strip 29 i-s heated to a liquid state by e the die it. rIhematerial forming the strip 2li may be composed of polymerizedvinyl-chloride, a copolymer of vinyl-acetate and vinyl chloride,polystyrene, cellulose acetate, ester gum, tar, pitch, other [bituminousmaterials, or any other suitable exible thermoplastic material, and thematerial may' contain any suitable plasticizers, if needed. The meltedthermoplastic material ac cumulates over the entrance to the die openinglll and the pressure of the accumulation and the movement of theconductor l0 and the textile covering i3 thereon downwardly, as viewedin Fig. 2, causes the material to flow through the entrance oi andthrough the die opening i5. The entrance to the die opening l5 isbell-shaped 2o and tapered and serves to build up the pressure of theaccumulated thermoplastic material and thereby increase its dow. Thus,a. layer t@ (Figs. 2 and 3) of the thermoplastic material is formed overthe 'textile covering I3. The layer 36 is cooled and hardened as it isdrawn from the rounded exit of the die opening i5 and with the textile`covering it and the conductor lo forms an insulated cord ti. v

As the textile covering i3 is drawn through the die openingI it, thehot, highly liquid thermoplastic material enters the interstices of thetextile covering to thoroughly impregnate the covering. The relativelycold portions of conductor i@ and covering i3, as they are initiallydrawn into the accumulation oi hot liquid thermoplastic material, causea firm skin of the material to be 'formed'on the covering i3, which skintends to center 'the conductor lil and covering it thereon in the dieopening it. The pairs of rollers l--i 2 and illlil also aid in centeringthe conductor it and the covering i3 thereon in the die opening i5 asthey are drawn therethrough. The restoring pressure of the accumulationof the liquid thermoplastic material, if the conductor it and coveringi3 thereon pass eccentrically through the opening ill and therebydisturb the how of the material through that opening, tends to centerthe conductor in the opening,

The thickness of the layer 30 may be controlled by varying thetemperature or composition of the thermoplastic material to vary itsviscosity, or by using dies having openings of dierent diameters. Thesize and taper ofthe bell-shaped entrance also aects the thickness ofthelayer til. That is, if a thicker layer is desired it may be obtained byusing a die havinga die opening with a longer and more taperingbell-shaped entrance. Conversely, if a .thinner-'layer is desirable,'adie having a die opening with a shorter and less tapered bell-shapedentrance may be used.

In placel of the knitting machine of which the knitting head Il forms aportion, it maybe desirable to use a braiding machine, a servingmachine, a pulp covering machine, or any other suitable type of coveringmachines, Smooth, uniforni coatings of any desired thicknesses may beapplied to either covered-or bare conductors by the processand apparatusherein described at a I very lowcost per unit of length of theconductors.

What is claimed is: 1. In an apparatus for covering conductors, a diehaving a passage formed. therethrough, said passage having a bell-shapedentrance, said die having a surface surrounding the entrance of thepassage for supporting thermoplastic material thereon, means forsupporting the die with the bell-shaped entrance facing upwardly, meansfor advancing a conductor downwardly through the passage, means forguiding a conductor being advanced by the advancing means through thecenter of the passage, means for feeding solid thermoplastic materialtoward the entrance of the passage, and means for heating the die toliquefy the thermoplastic material being fed to the entrance of thepassage, whereby the thermoplastic material ows around the conductor andisdrawn therewith through thevpassage.

2. In an apparatus for covering conductors, a die having a passageformed therethrough, said passage having 4a bell-shaped entrance, meansior supporting the die with the bell-shaped entrance directed upwardly,the surface of the die surrounding the entrance of the passage beingsumciently wide to hold material thereon, means for heating the/di,means for feeding thermoplastic material to thel upper end ofthepassage, a heat;

ing coil associated with the die to heat the die. wherebythermoplasticmaterial fed by the feeding means is liquefied andaccumulates over the passage, and means for advancing such a conductordownwardly through theaccumulated and liqueiied thermoplasticmaterial-and through the ".a vertically disposed die-opening formed inthe .central portion thereon-said die/opening having a bell-shaped upperportion, meansfor liquefying passage, whereby the covering on Jtheconductor is impregnated Iwith the thermoplastic material.

4. An apparatus for-covering conductors, which consists of `ahorizontally disposed block having a thermoplastic material positionedonthe top of said block, and means for advancingl a conductor downwardlythrough Asaid die opening.

5. An apparatus for covering conductors, which consists ora horizontallydisposedblock having a vertically disposed die opening formed in thecen-- trai portion thereof, said die opening .havinga tapered entranceportionsaid block a -top surface surrounding the ventrance portion oflthe -die opening for supporting thermoplastic material thereon, meansfor heating the thermoplastic material positioned on said supportingsurface of the block,` and means for advancing aconductordownwardlythrough said die opening.

6. An apparatus for covering conductors, which consists of ahorizontally disposed block having a vertically disposed die openingformed centrally therein, said block having on the top thereof a surfacesurrounding the die opening for supporting a covering material, the topportion of said-die opening being bell-shaped and the lower portion ofsaid die opening being rounded, means for heating said block to liquefythe covering material, .and means for advancing a conductor downwardlythrough said passage.

ciently wide to support thermoplastic material thereon, means forsupporting the' die in a horizontal position with the larger portion ofthe passage positioned at`the -uppersurface of the die, means forfeeding a strip of thermoplastic ROBERT T. ADAMS. f

REFERENCES CITEDl The. following references are of record in the file ofthis patent: i

UNITED STATES yPA'IETN'll-S v Number Name Date 2,291,720 Hukle Aug. 4,1942 1,972,756 Blaisdell Sept. 4,1934 2,057,789 Petersen Oct. 20, 19361,094,879 Cobb Apr; 28, 1914 1,646,825 Kochendorfer Oct. 25, 19271,802,605 Kemp Apr. 28, 1931 2,199,067 Bradt Apr.- 30, 1940 2,354,260Haney et al. July 25, A1944 2,011,615 Choice et al Aug. 20, 19352,155,403 Cook Apr. 25, 1939 2,293,379

Bruining Aug. 18, 1942

